From 0bb5e7b021c3c0a125f57739935964c499e7361b Mon Sep 17 00:00:00 2001
From: Jake Hillion <jake@hillion.co.uk>
Date: Wed, 9 Feb 2022 12:19:46 +0000
Subject: [PATCH] wip: tracing process and its children

---
 .gitignore            |  42 +++
 .vscode/settings.json |   4 +
 Cargo.lock            | 680 ++++++++++++++++++++++++++++++++++++++++++
 Cargo.toml            |  14 +
 src/error.rs          |   7 +
 src/main.rs           | 117 ++++++++
 6 files changed, 864 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 .vscode/settings.json
 create mode 100644 Cargo.lock
 create mode 100644 Cargo.toml
 create mode 100644 src/error.rs
 create mode 100644 src/main.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e4ade95
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,42 @@
+
+# Created by https://www.toptal.com/developers/gitignore/api/visualstudiocode,rust
+# Edit at https://www.toptal.com/developers/gitignore?templates=visualstudiocode,rust
+
+### Rust ###
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+
+### VisualStudioCode ###
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/*.code-snippets
+
+# Local History for Visual Studio Code
+.history/
+
+# Built Visual Studio Code Extensions
+*.vsix
+
+### VisualStudioCode Patch ###
+# Ignore all local history of files
+.history
+.ionide
+
+# Support for Project snippet scope
+
+# End of https://www.toptal.com/developers/gitignore/api/visualstudiocode,rust
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..c95a33d
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,4 @@
+{
+    "editor.defaultFormatter": "rust-lang.rust",
+    "editor.formatOnSave": true
+}
\ No newline at end of file
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..dd424ac
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,680 @@
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+# It is not intended for manual editing.
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+
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+ "ctor",
+ "version_check",
+]
+
+[[package]]
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+ "cfg-if",
+ "wasm-bindgen-macro",
+]
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+ "bumpalo",
+ "lazy_static",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
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+ "js-sys",
+ "wasm-bindgen",
+ "web-sys",
+]
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+ "wasm-bindgen-macro-support",
+]
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+ "proc-macro2",
+ "quote",
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+ "wasm-bindgen-shared",
+]
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+]
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+ "cc",
+]
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+[[package]]
+name = "winapi"
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+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
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+[[package]]
+name = "winapi-util"
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+checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..cd5e41f
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "forktop"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+log = "0.4"
+env_logger = "0.9"
+thiserror = "1"
+async-std = "1"
+
+nix = "0.23.1"
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..83b5e76
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,7 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("{msg}: {src}")]
+    Nix { msg: &'static str, src: nix::Error },
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..442aceb
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,117 @@
+use log::{error, info};
+
+mod error;
+
+use error::Error;
+
+use std::collections::HashMap;
+use std::ffi::{CStr, CString};
+use std::sync::Arc;
+
+use async_std::sync::Mutex;
+use async_std::task;
+
+use nix::sys::ptrace::{self, Options};
+use nix::sys::signal::Signal;
+use nix::sys::wait::{wait, WaitStatus};
+use nix::unistd::Pid;
+use nix::unistd::{self, ForkResult};
+
+struct ProcessDescription {
+    parent: Option<Pid>,
+    name: Option<String>,
+}
+
+enum ProcessState {
+    Traced,
+    Completed(u8),
+}
+
+fn main() -> Result<(), Error> {
+    env_logger::init();
+
+    info!("forking child process...");
+
+    let child = unsafe {
+        match nix::unistd::fork().map_err(|e| Error::Nix {
+            msg: "fork",
+            src: e,
+        })? {
+            ForkResult::Parent { child } => child,
+            ForkResult::Child => {
+                let err = spawn_child();
+                error!("error spawning child: {}", err);
+                std::process::exit(1);
+            }
+        }
+    };
+
+    task::block_on(async_main(child))
+}
+
+async fn async_main(child: Pid) -> Result<(), Error> {
+    let children = Arc::new(Mutex::new({
+        let mut m = HashMap::new();
+        m.insert(
+            child,
+            ProcessDescription {
+                parent: None,
+                name: Some("main".to_string()),
+            },
+        );
+        m
+    }));
+
+    ptrace::setoptions(
+        child,
+        Options::PTRACE_O_TRACECLONE
+            | Options::PTRACE_O_TRACEFORK
+            | Options::PTRACE_O_TRACEEXIT
+            | Options::PTRACE_O_TRACEVFORK,
+    )
+    .map_err(|e| Error::Nix {
+        msg: "ptrace_setoptions",
+        src: e,
+    })?;
+
+    while !children.lock().await.is_empty() {
+        let wait_result = wait().map_err(|e| Error::Nix {
+            msg: "wait",
+            src: e,
+        })?;
+
+        match &wait_result {
+            WaitStatus::Signaled(pid, Signal::SIGTRAP, _) => {
+                ptrace::cont(*pid, None).map_err(|e| Error::Nix {
+                    msg: "ptrace_cont",
+                    src: e,
+                })?;
+            }
+            _ => unimplemented!(),
+        };
+    }
+
+    Ok(())
+}
+
+fn spawn_child() -> Error {
+    fn int() -> Result<(), Error> {
+        ptrace::traceme().map_err(|e| Error::Nix {
+            msg: "traceme",
+            src: e,
+        })?;
+
+        let sh = CString::new("/bin/sh").unwrap();
+
+        unistd::execve::<_, &CStr>(&sh, vec![&sh].as_slice(), &[]).map_err(|e| Error::Nix {
+            msg: "execve",
+            src: e,
+        })?;
+
+        unreachable!()
+    }
+
+    int().expect_err("execve doesn't return on success")
+}
+
+async fn wait_loop(desc: &mut HashMap<Pid, ProcessDescription>) {}